How to conflict Network Admin for Multisite after point out domain name position? Help!!!

My hosting provider supporter point my domain to root folder from wordpress folder to make sub-domain work he said, then everything works fine but I can’t login my wordpress admin (name and password not correct) so I’ve login my omnim (it’s work) but when I want to access My site -> Network Admin -> dashboard it didn’t work it’s show the simple blog not the Admin dashboard,he said i have to re-install wordpress multisite to fix this issue but I worried my another wordpress site will lost the content,images link etc.. so is there anyway to conflict the Network Admin by hand not to re-install it? please help.

thank you, Decneo